Air damper control for refrigerators

ABSTRACT

A refrigerator has a frozen food compartment maintained at subfreezing temperatures and a food-cooling compartment maintained at temperatures above freezing by circulation of chilled air through the compartments, the air being chilled by passing it over an evaporator operated at subfreezing temperatures in an air duct. A thermostatically actuated damper regulates the flow of chilled air into and through the foodcooling compartment according to the temperature in the cooling compartment. The damper comprises two face-to-face grilles each having a multiplicity of slots alignable with the slots of the other grille and one grille is shifted by a thermostatic element relative to the other to align more or less of the slotted areas. The thermostatic element is a vapor-filled bellows located in a housing in the chilling compartment and adjacent the air inlet. When the grilles are open air is aspirated from the compartment through the housing and in contact with the bellows and returned to the compartment with the chilled air.

Waited States Patent Honk [ Feh.29,11972 [54] AER DAMPER CONTROL FORREFRHGERATDRS William J. Honk, Columbus, Ohio [73] Assignee: Rancoincorporated, Columbus, Ohio [22] Filed: June 1, 1970 [21] Appl. No.:41,851

[72] Inventor:

Primary Examiner william J. Wye Attorney-Watts, Hoffmann, Fisher &Heinke [57] ABSTRACT A refrigerator has a frozen food compartmentmaintained at subfreezing temperatures and a food-cooling compartmentmaintained at temperatures above freezing by circulation of chilled airthrough the compartments, the air being chilled by passing it over anevaporator operated at subfreezing temperatures in an air duct. Athermostatically actuated damper regulates the flow of chilled air intoand through the food-cooling compartment according to the temperature inthe cooling compartment. The damper comprises two face-to-face grilleseach having a multiplicity of slots alignable with the slots of theother grille and one grille is shifted by a thermostatic elementrelative to the other to align more or less of the slotted areas. Thethermostatic element is a vapor-filled bellows located in a housing inthe chilling compartment and adjacent the air inlet. When the grillesare open air is aspirated from the compartment through the housing andin contact with the bellows and returned to the compartment with thechilled air.

4 Claims, 5 Drawing Figures AIR DAMPER (IONTROL FOR REFRIGERATORSBACKGROUND OF THE INVENTION In certain types of food storagerefrigerators two compartments are provided in a single cabinet. One ofthe compartments is maintained at subfreezing temperatures for storageof frozen foods and the other compartment is maintained at abovefreezing temperatures for preserving fresh foods. The desired chillingof the compartments is effected by forcing air to circulate from thecompartments and through a passageway having a refrigerator evaporatorunit therein which chills the air to subfreezing temperatures inaccordance with the cooling requirements of the freezing compartment.The chilled air is then directed into the freezing compartment. Thetemperature of the food-cooling compartment is maintained at abovefreezing temperatures by admitting more or less of the subfreezingtemperature air from the passageway into the chamber through an airinlet controlled by a damper. I-Ieretofore, the damper generallycomprised a vane adapted to swing to and from the air inlet opening inaccordance with expansion and contraction of a thermostatic elementsubjected to the temperature in the cooling compartment. The mostsatisfactory type of thermostatic element was a vapor-filled bellowshaving a capillary sensing tube attached thereto and containing asuitable temperature responsive vapor. The capillary tube was extendedand coiled in an area of the cooling compartment representative of theaverage temperature in the compartment. Because the bellows was locatedadjacent the damper it was subjected to the subfreezing temperatureofthe chilled air entering the compartment. Consequently, thetemperature of the bellows tended to be lower than that to which thecapillary tube was subjected. As is well known, the vapor pressure inthe bellows and its tube corresponds to the temperature at the coolestportion of the bellows and tube. Accordingly, to cause the bellows torespond to the temperatures sensed at the coiled tube portion it hasbeen necessary to heat the bellows by an electrical heating element andmaintain its temperature above the temperature of the sensing portion ofthe capillary tube. This expedient is relatively expensive not onlybecause of the cost of incorporating the heating element in the controlstructure but also in the provision of electrical power connections forthe heating element.

Another problem encountered with known refrigerators of the typementioned is that the subfreezing temperature air enterin g the foodstorage compartment tends to freeze foods adjacent the air inlet.

THE PRESENT INVENTION An important feature of the invention is theprovision of means for causing the air entering the cooling compartmentthrough a thermostatically operated damper to aspirate air from thecompartment and through a housing for the thermostat so that thethermostat is subjected to air having a temperature representative ofthe average temperature in the cooling chamber. Thus, heating of abellows type thermostat by an electric heater is obviated and moresatisfactory temperature control is achieved. Furthermore, the aspiratedcompartment air mixes with the subfreezing temperature air and raisesits temperature and reduces or deviates the tendency of fresh foods tofreeze in the compartment.

Other objects and advantages of the present invention will becomeapparent from the following detailed description thereof made withreference to the accompanying drawings which form a part of thespecification.

FIG. 1 is a schematic illustration of a refrigerator embodying theinvention;

FIG. 2 is a sectional view of an air damper control for the refrigeratorshown in FIG. 1, the section being taken along line 22 ofFIG. 3;

FIG. 3 is a sectional view taken substantially along line 3-3 of FIG. 2;and

FIGS. 4 and 5 are fragmentary sectional views of two grilles takensubstantially along line 44 of FIG. 3, on a larger scale, showing thegrilles in two different relative positions.

Referring to FIG. 1, a refrigerator embodying the invention is shown at10. The refrigerator 10 comprises a cabinet 11 having a frozen foodstorage compartment 12 and a food cooling compartment 13 for storage offresh foods. The compartments l2 and 13 are separated by a vertical airpassage or duct 14 formed by two spaced parallel vertical walls 15, 16,a rear wall 17 and a front wall, not shown. The construction of therefrigerator 10 is well known in the art and need not be shown infurther detail for an understanding of the disclosure.

A refrigerator evaporator 20 forming an air chilling unit, is located inthe duct 14 and has air-cooling fins between which air is forced by ablower 21 directing air upwardly through the duct. The blower 21circulates air from the compartment 12 through the evaporator fins andback into the compartment 12. The air circulation path includes anopening 22 between the lower portion of the compartment 12 and the duct14 and an opening 23 between the duct and the upper portion of thecompartment. The path of circulation of the air is shown by arrows.

The evaporator 20 is a part of a conventionalcompressorcondenser-evaporator type refrigerating system and to avoidunnecessary description, the compressor and the controls therefor arenot shown. Suffice to say, the refrigerating system is cycled by atemperature control responsive to the air tem perature in thecompartment 12 so as to maintain the air circulated therein from theevaporator 20 at a predetermined minimum temperature, such as 10 F.

The temperature of the air in food-cooling compartment 13 is controlledby admitting more or less of the air discharging from the evaporator 20into the top of the compartment through an opening 24 between the duct14 and the compartment. The flow of air into the compartment 13 throughthe opening 24 is controlled by a temperature-responsive dampermechanism 25. Air is returned to the duct 14 from the compartment 13through an opening 26. As the temperature of the air in the compartment13 tends to rise above a given desired temperature, such as 42 F., thedamper mechanism 25 admits a greater volume of the chilled air into thecompartment. As the temperature of the air inside the compartment 13 isreduced towards that desired the flow of air into the compartment isthrottled by the mechanism 25.

The temperature-responsive damper mechanism 25 comprises a grille frame27 and a thermostatic mechanism 28. The frame 27 is preferably formed ofa suitable molded material and includes a.hollow boxlike structurehaving a rectangular opening 30 in one side thereof and a rectangularoutlet opening 31 in the opposite side. A flange 32 is formed about theinlet opening 30 and has openings by which the frame can be attached bysuitable fasteners, not shown, to the air duct wall 15 and in theopening 24. The flange 32 surrounds the edges of the opening 24 andforms a seal so that air flow into the compartment 13 is effected onlythrough the frame openings 30 and 31.

A panel-type grille 33 extends transversely of the opening 30. The edgeportions of the grille 33 abut a shoulder 34 formed about the inner endedges of the opening 30 and are cemented to the shoulder by a suitableadhesive. The grille 33 has a multiplicity of relatively narrowlongitudinally extending slots 35 formed therein. The slots 35 areregularly spaced and parallel to one another. The slots 35 areinterrupted at the central portions thereof. Preferably, the grille 33is formed of a plastic material of the type presenting a low coefficientof friction and its inner face is slightly embossed or raised in theslotted area, as seen at 36 in FIG. 2. The embossed face portion is flatand smooth.

A second grille 37 which is substantially identical in shape, materialand form to the grille 33 is arranged with an embossed flat face 38thereof slidingly engaging the embossed face 36 of the grille 33. Thegrille 37 has a multiplicity of slots 40 which correspond in spacing andwidth to the slots 35. The slots 40 are interrupted at their centralportions so that the grille 37 has a solid panel portion 41 at itscenter. The material between the slots 40 fonn bars 42 and the width ofthe bars are greater than the width of the slots. The bars 42 serve toblock the passage of air through the slots when the grille 40 is movedto its lowermost position. The confronting surfaces of the embossedportions of the grilles 33, 37 effectively seal the inner edges of theslots 35 when the bar portions 42 thereof close the slots.

The grille 37 is maintained in sliding engagement with the grille 33 bya strip bow spring 43. One end of the spring 43 is inserted into a slotin a block 44 formed on the lower wall 45 of the frame 27 and engagesthe portion 41 of the grille 37 and urges the latter to the grille 33.

When the grille 37 is in its lowermost position the bars 42 thereofregister with the slots of the grille 37 and prevent air from passingthrough the frame 27 and into the cooling chamber 13. This condition isshown in FIG. 5. As the grille 37 is raised, the slots 40 thereofregister with the slots 35 thereby permitting passage of air into thecooling chamber 13, as seen in FIG. 4. When the grille 37 has raised toa predetermined position the slots 40 thereof will be in exactregistration with the slots 35, as seen in FIG. 4, and full flow of airinto the chamber 13 is effected. It will be obvious that the stream ofair flowing from the frame outlet 31 and into the compartment 13 will beconsiderably diffused by the multiplicity of the air slots 35, 40 andconsequently turbulence adjacent the control mechanism is minimized.

A narrow slot 46 is formed through the bottom wall 45 of the frame 27and extends transversely of the frame. The walls of the slot 46 slopeupwardly towards the outlet opening 311 When air flows from the inlet tothe outlet 31, a low-pressure area is created over the slot 46 and airis induced to flow upwardly through the slot.

To facilitate assembly, the frame-27 comprises two molded members 47,48. The member 47 has the opening 30 formed therein and the other member48 includes the opening 31. The member 47 has a rectangular lip or edge49 to which a corresponding lip or edge on the member 48 is secured,such as by cement or fusion,

The thermostatic mechanism 28 is mounted in a sheet metal housing 50which is attached to the lower wall 45 of the frame 27. The housing 50comprises a channel-shape member 51 which has laterally extendingflanges 52,53 which are secured to the underwall of the frame 27 byscrews 54. The housing 50 depends beneath the frame 27 and is disposedin the compartment 13. The lower wall 45 of the frame 27 forms the upperwall of the housing 51 and the lower opening of the slot 46 extendslengthwise of the interior ofthe housing.

A metal bellows 57 is supported on the bottom wall of the housing 50 andreciprocates the grille 40 vertically by expansion and contractionthereof. The bellows 57 contains a suitable vapor which expands andcontracts in accordance with increases and decreases in temperature andtends to cause corresponding expansion and contraction of the bellows.The bellows 57 is comprised of three wafer shape capsules 58 arranged instacked relation. Each capsule is formed of thin dish-shaped metaldiaphragms hermetically joined about their peripheries. The centralportions of the diaphragms have bosses 59 and the bosses of adjacentdiaphragms are brazed to one another. The joined bosses 59 haveregistered openings so that the capsule interiors are interconnected.The lowermost capsule 58 is attached to a support plate 60 which issecured over an opening 61 in the bottom wall of the housing 50. One endof a capillary tube 62 is brazed in an opening through the plate 60 andthe boss 59 of the lower wafer 58. The other end of the capillary tubeis sealed and a portion of the sealed end of the tube is formed in ahelix 63. The helix 63 is supported at one end of the housing 50 by abracket 64. The bellows 57 and tube 62 contain a thermally responsivegas in vapor phase suitable for providing appreciable changes in vaporpressures in the temperature range to be controlled.

The boss 59 on the uppermost wall of the bellows has a post 65 attachedthereto, the upper end of which engages in a dimple formed in the lowerwall of the lever 66. When the bellows 57 expands, the post 65 is movedaxially upwardly and moves the lever 66 to transmit motion of thebellows to the grille 37.

The lever 66 is comprised of a sheet metal stamping in the form of achannel and is pivoted at one end by lugs 67 formed on opposite sidesthereof. The lugs extend into openings or notches in opposite sides ofthe housing 50. This mechanical expedient for pivoting the lever 66 iswell known in the art, and the details are unnecessary to theunderstanding of the invention.

The grille 37 has a stem 70 attached to the central lower portionthereof, which stem projects downwardly through an opening 71 formed inthe bottom wall 45 of the frame 27. The stem 70, and the grille 37, isurged downwardly by a compression spring 72 which surrounds the stem andhas one end engaging in a recess in the wall 45 and the opposite endengaging a shoulder or washer 73 on the lower end of the stem. The stem70 engages the lever 66 adjacent the free end of the lever so thatvertical movements of the post 65 are imparted to the stem 70 andmultiplied by the lever.

The lever 66 is loaded by a spring for resisting expansive movement ofthe bellows 57. One end of the spring 80 is hooked to the lever 66, asshown, and the opposite end is threaded on a screw 81 which is rotatablysupported in an adjusting lever 82. The lever 82 is formed by achannel-shape sheet metal member and the opposite sides thereof arepivoted on a pin 83. The ends of the pin 83 are supported in openingsthrough the opposite sidewalls of the housing 50, as shown. The tensionof the spring 80 tends to rotate the lever 82 clockwise, as viewed inFIG. 3, which movement is limited by a nut 84 threaded on an adjustingscrew 85 and engaged by the lever. The adjusting screw 85 is rotatablypositioned in the bottom wall of the housing 50 and the upper endextends through an opening through a dimpled portion of the lever 82.The screw 85 may be rotated by lugs 86 formed on a driving plate havinga serrated opening which meshes with a serrated portion of the screw 85.An adjusting knob, not shown, may be fitted over the lugs 86 tofacilitate rotation of the screw.

The tension of the spring 80 applies a load to the bellows 57 throughthe lever 66 and post 65. The tension of the spring 80 is such as tocollapse the bellows 57 and move the lever 66 to its lowermost positionwhen the temperature in the compartment 13 is at a desired minimum. Theminimum temperature may be 42 F., for example. In this position, theslots 35 of the air grille 33 will be closed and no air will enter thecompartment 13 through the frame 27. As the temperature of the air inthe compartment 13 rises above 42 the bellows 57 commences to expand andmove the lever 66 against the load of the spring 80 and raise the grille37. The raising of the grille 37 gradually uncovers a greater area ofthe slots 35 so that flow of cold air into the chamber 13 is effected.When the temperature at the bellows 57 decreases, the bellows collapseand the grille 37 is lowered and throttles the flow of air into thecompartment 13. Thus, the temperature of the compartment 13 ismaintained at a substantially constant degree, according to the tensionof the spring 80. The temperatures at which the grille 37 is actuatedcan be adjusted by varying the tension of the spring 80 by setting thescrew 85. Calibration of the spring 80 is effected at the factory byadjusting the screw 81 to provide the proper setting of the springtension for a given position of the screw 85.

As air flows through the frame 27 and into the chamber 13 through theopening 31 a low pressure exits above the slot 46 in wall 45 of theframe. The low pressure induces air to enter the housing 50 from theupper portion of the chamber 13 and flow through the slot 46. Air entersthe housing through the open ends thereof and through gaps in thehousing walls exiting at the ends of the channel 51, about the opening61 and the openings for the screws 81, 85. The flow of air from thecompartment 13 into the housing 50 causes both the capillary tube 63 andthe bellows 57 to sense the same air temperature. The vapor pressureinside the bellows 57 will therefore correspond to the changes intemperature of the air from the compartment 13. The housing 50 shieldsthe bellows from direct contact with the cold air entering thecompartment through the frame outlet 31. By creating a flow of air fromthe compartment 13 through the housing 50 and directing diffused airinto the compartment, the bellows 57 will not be affected by the coldairstream and require application of heat thereto. Furthermore, airdrawn from the compartment upwardly through the slot 46 mixes with theair passing to the frame outlet 31 and tempers the below freezingtemperature air and eliminates or reduces the tendency for fresh food tobe frozen in the compartment 13.

lclaim:

1. A refrigerator having a compartment to be cooled, an air chillingunit and means to force air into heat exchange relation with thechilling unit and through an air duct having an opening communicatingwith the interior of said compartment, air flow control means in saidopening and comprising, a structure defining an air flow path, airdamper means associated with said airflow path and including a movablemember for controlling the flow of air through said airflow path, athermally responsive power element in said compartment operable toactuate said movable member, wall means forming an air channelinghousing about said power element and including an air inlet from saidchamber, and means forming a venturi opening between said air path andthe interior of said air channeling housing.

2. A refrigerator as defined in claim 1 further characterized by saidwall means comprising a housing attached to said frame, and said powerelement comprising a bellows in said housing having a vapor fill, and alever interconnecting said bellows and said damper.

3. A refrigerator as defined in claim 2 further characterized by saidhousing and said venturi opening comprising a slot extending across thetop wall of said housing, and said housing being open at least at oneend.

4. A refrigerator as defined in claim 3 further characterized by saidhousing comprising a channel-shape member having air inlet openings inopposite ends.

1. A refrigerator having a compartment to be cooled, an air chillingunit and means to force air into heat exchange relation with thechilling unit and through an air duct having an opening communicatingwith the interior of said compartment, air flow control means in saidopening and comprising, a structure defining an air flow path, airdamper means associated with said airflow path and including a movablemember for controlling the flow of air through said airflow path, athermally responsive power element in said compartment operable toactuate said movable member, wall means forming an air channelinghousing about said power element and including an air inlet from saidchamber, and means forming a venturi opening between said air path andthe interior of said air channeling housing.
 2. A refrigerator asdefined in claim 1 further characterized by said wall means comprising ahousing attached to said frame, and said power element comprising abellows in said housIng having a vapor fill, and a lever interconnectingsaid bellows and said damper.
 3. A refrigerator as defined in claim 2further characterized by said housing and said venturi openingcomprising a slot extending across the top wall of said housing, andsaid housing being open at least at one end.
 4. A refrigerator asdefined in claim 3 further characterized by said housing comprising achannel-shape member having air inlet openings in opposite ends.